The most common dermal manifestation resulting from primary infection with varicella-zoster virus (VZV) is chickenpox (varicella), which generally occurs in early childhood. Reactivation of latent virus occurs in about 10-20% of adults and produces vesicles that are typically confined to a single dermatome of the skin (herpes zoster). VZV infections can cause systemic infections of the central nervous and respiratory systems in immunologically competent patients and produce disseminated disease of multiple organ systems in those with impaired immunologic defenses. Laboratory diagnosis is important for distinguishing herpes simplex virus (HSV) from VZV infections since clinical presentation of herpes zoster due to VZV can be confused with the dermal distribution produced by HSV.